[Gout - a common and well known disease].

Hyperuricemia is defined by a blood urate level > 405 µmol/L, the cut-off value at which urate forms crystals in vivo. In 15-20% these individuals develop gout, clinically characterized by attacks of acute arthritis, initially and most commonly affecting MTP 1 or other joints, tendons and soft tissues of the foot. These attacks usually subside within 1 to 2 weeks. Over time attacks occur more frequently and can transform into chronic arthritis characterized by tophi. The gold standard for diagnosis relies on identification of urate crystals by polarization microscopy in aspirated joint fluid. This procedure is rarely performed in primary care where the majority of patients are seen, and gout is usually diagnosed by clinical criteria. New imaging technologies (ultrasound, dual-energy CT) can be helpful when aspiration is not available and when the diagnosis is unclear. Gout has a prevalence of 1.7% and incidence rate of approximately 200 per 100000 person-years in Sweden, figures that increase over time.